Job opportunities for women in the 1920s a. expanded rapidly in Hollywood and radio. b. expanded dramatically. c. existed mainly in the area of education. d. tended to cluster in a few low-paying fields. e. offered higher-paying positions than before.

Tended to cluster in few low-paying field.

Explanation:

Though with the passage of the nineteenth amendment, women of the United States got the right to vote, their traditional roles could be left behind so easily and most of the women were confined to households. In the 1920s there were new job opportunities like clerical work, textile industry but the number of women engaged in these fields was still low and were paid less than their male counterparts.

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.        

c. wright mills's sociological imagination suggest investigating to explain this increase?